Biotropica最新文献

We quantitatively tested the riverine barrier hypothesis and its influence on biogeographical distributions and molecular variation in New World monkeys (Parvorder: Platyrrhini). Using mitochondrial markers (cytochrome oxidase subunit II and cytochrome b), we analyzed taxonomic differences and the effects of geographical barriers on molecular patterns across Central and South America. Nearly 80% of described species are separated by geographical barriers, including several mountain chains. River width exhibited a negative correlation with molecular similarity in adjacent taxa for both molecular markers. Several presently described taxa were not supported based solely on these molecular phylogenetic markers, including Saimiri, Mico, Cebus, Sapajus, and Cherecebus. These taxonomic issues are far more common where river barriers do not exist. In conclusion, we found a significant correlation between river width and molecular divergence in adjacent taxa, indicating that wider rivers were associated with greater molecular divergence for two commonly used mitochondrial genes. Species boundaries were predominantly found at river interfaces, and in the absence of discernable geological barriers, adjoining species were more likely to exhibit molecular similarity. Our findings suggest that river and mountain barriers are significantly associated with gene flow for neotropical primate taxa. Additionally, river width proves to be a valuable tool for estimating molecular divergence in adjacent taxa, particularly in regions with limited sampling.

Drought tolerance is an integral determinant of drought survival in trees; thus, an accurate and rapid assessment of drought tolerance can lead to improved prediction of forest responses to droughts. The osmometer method enables the rapid determination of the leaf water potential at turgor loss (π_tlp), a key parameter of drought tolerance, from the osmotic potential at full turgor (π_sat). However, despite its wide applications, there have been few validations in ever-wet tropical rainforests. Here, we assessed the efficacy of the osmometer method in dipterocarps, a dominant tree group in SE Asia in ever-wet Malaysia, and examined the linkage between π_tlp and distribution along a rainfall gradient. The π_tlp determined using the conventional method was strongly and linearly correlated with the π_sat determined using an osmometer. The coefficients of our model were statistically identical to those previously represented, but with a slightly larger intercept (0.21 MPa). Species with more negative π_tlp were distributed in drier habitats, with a relatively larger variation in π_tlp for species confined to ever-wet climates than for those occurring in ever-wet and seasonally dry climates. Some leaf traits, individual leaf area and dry matter content, were associated with π_tlp, but these traits alone could not predict species distribution. We demonstrated the robustness of the osmometer method in ever-wet tropical rainforest species and that π_tlp is associated with current distribution along large-scale moisture availabilities.

The Cerrado is a highly threatened biome that harbors a great portion of Brazilian biodiversity, including many endemic species. Such richness may reflect its environmental heterogeneity, which includes different vegetation types (from grasslands to forests). Several endemic species in the Cerrado are strongly associated with open vegetation types. Recent studies have shown that woody encroachment can negatively impact several components of biodiversity. In the present study, we provide information on variation in lizard diversity across different vegetation types in a protected area located in the southern portion of the Cerrado and evaluated the effect of vegetation density on lizard taxonomic, functional, and phylogenetic diversity. We predicted that the three aspects of lizard diversity would be negatively affected by vegetation density and that Beta diversity would vary significantly across the vegetation gradient. We confirmed nearly all of our predictions, except for functional diversity, which, contrary to our expectations, was positively influenced by vegetation density. We also found that Beta diversity indices based on both species composition/abundance and phylogenetic features of communities experience a significant turnover across the vegetation density gradient. This study greatly strengthens previous studies that suggest a negative impact of vegetation density (and, consequently, woody encroachment) on lizard diversity. Therefore, managers of protected areas in the Cerrado should consider the use of strategies to avoid woody encroachment, like fire management with prescribed fires.

Tree phenology plays an important role in determining the structure and function of tropical forest communities. However, there are few long-term studies on tree phenology from South Asia. We monitored 716 trees of 54 species monthly from 2011 to 2023 for leaf flush, flowering, and fruiting in the Pakke Tiger Reserve, Arunachal Pradesh, and North-east India. We examined monthly patterns in the percentage of species and trees in leaf flush, flower, and fruit and characterized phenological seasonality using circular statistics. We hypothesized that phenological patterns would show significant seasonality, with phenological activity being triggered by increasing solar irradiance and daylength. Flowering periodicity was classified using Fourier analysis, and we examined the relationships between phenological activity and temperature, rainfall, solar radiation, and daylength using GAMLSS. Leaf flush and flowering were moderately seasonal, peaking in the warm dry season. Fruiting patterns and their seasonality differed among dispersal modes. Most species (78.13%) and trees (51.17%) flowered annually. In accordance with our hypothesis, daylength and solar radiation served as proximate cues for phenological activity through nonlinear effects. This indicated the existence of narrow ranges of optimal climatic conditions for phenology. Rainfall was not an important proximate cue as water availability was not a constraint for tree phenology in the site. Our study is the first long-term phenological monitoring effort that establishes the proximate climatic cues for the observed patterns of leaf flush, flowering, and fruiting in the seasonal tropical forests of the Eastern Himalaya.

Pollination is an important ecological process for plant reproduction. Understanding the differences in plant–pollinator interactions and pollinator importance across spatial scales is vital to determine the responses of these interactions to global changes. Continental and oceanic island systems provide us with an ideal model to examine the variation in plant–pollinator interactions. Here, we compared the differences in species composition, plant–pollinator network structure, and pollinator importance in communities between a continental island (Wanshan Island) and an oceanic island (Yongxing Island) in China. The results reveal highly dissimilar species composition between continental and oceanic islands that caused highly different plant–pollinator network structures. In particular, the oceanic island networks had higher network connectance, nestedness, and specialization than the continental island networks. For plants cooccurring on both islands, pollinator species richness and flower visitation rate were higher on the continental island than on the oceanic island. Plant niche overlap was higher on the oceanic island than on the continental island, while pollinator niche overlap was higher on the continental island than on the oceanic island in both the entire network and cooccurring plant species subnetwork. Hymenoptera was the most important pollinator group in the continental island community, while Apidae was the most important in the oceanic island community. The results imply that oceanic island communities may be less vulnerable to disturbance, such as habitat alteration or destruction, than continental island communities and provide implication insights into biodiversity conservation for pollinators on islands.

Management of degraded tropical forest fragments is usually done by cutting climbers (cutting). However, it is still necessary to understand the outcomes of cutting in combination with planting native tree species' seedlings (cutting + planting), especially on the edges of fragments, which are subject to higher disturbance than the forest interior. We tested whether cutting + planting is the restoration strategy that most improves structural attributes of a degraded edge of a tropical seasonal semideciduous forest fragment in southeastern Brazil, relative to cutting and the absence of management (control). Linear mixed models revealed that, after an eight-year period, cutting + planting resulted in the highest decrease in the density and basal area of climbers longer than 1 m, and in the highest increase in the density of large living trees (diameter at breast height, DBH, ≥ 4.8 cm). Although cutting + planting decreased the percentage of large dead trees and increased tree sapling (DBH < 4.8 cm and total height ≥ 50 cm) richness, these variables were more affected by cutting. Management had no effect on the basal area of large living trees and tree sapling density. Because most structural attributes of the degraded edge studied were improved by cutting + planting, we advocate that it is the best strategy tested here for restoring tropical seasonal forests. We hypothesize that seedling planting improves forest conditions and stimulates recruitment, facilitating the regeneration of tree species. Thus, an interesting future avenue is to elucidate the mechanisms by which seedling planting affects regeneration and its long-lasting effects on forest structural attributes.